When dealing with perturbations, another ambiguity rises in the replacement of the momentum conjugate \(\pi _a\)  of the expansion factor \(a\)  in the effective potential of the scalar perturbations.
This ambiguity occurs not only in the dressed metric approach [cf. Eq.(REF )] but also in the hybrid approach [cf. Eq.(REF )], as it is closely related to the quantization strategy used in LQG/LQC,
because now only the holonomies (complex exponentials) of \(\pi _a\)  are defined as operators. Several choices have been proposed in the literature [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}.
In Secs.  and , we have shown that for some choices the effects on the power spectra are non-trivial, while for others the effects are negligible. However, even with the same choice,
the relative differences in the amplitudes of the power spectra among the three different models can be as large as \(100\%\)  in the infrared and intermediate regimes of the spectra, while in the UV regime
the relative differences are no larger than \(2\%\) , and the corresponding power spectra are scale-invariant. Since only the modes in the UV regime are relevant to the current observations, the power spectra
obtained in all the three models are consistent with current observations [9]}.
